Rotary boring-drill.



H. R. HUGHES.

' ROTARY BORING D APPLICATION FILED FEB. 4. 914.

1,143,272 Patented June 15, 1915.

s 'rn ATNT or W-E.

HOWARD a. HUGHES, or nous'rou, TEXAS, ,essrenon ro SHARP-HUGHES TOOL Y comrnnr, or HOUSTON, TEXAS, A ,ooaronarron or waxes.

ROTARY BORING-DRILL.

masses.

Specification of Letters Patent. Patented J1 1 1119 15, 11935,

APDlication filed February 24,1914. Seriallfl'o. 820,677.

others skilled in the art to which it apper tains to-make and use the same.

This invention relates to rotary boring drills ofthe'type that are equipped with rotatable cutters whose axes ofrotation are ;inclined downwardly and inwardlytoward the longitudinal axis -or vertical center of the drill head.

()ne object-bf my present invention is to provide a cutter for a drill of the type-mentioned which has a substantially frustoconical shaped-cutting portion of novel design that acts on the bottom of the hole, and an independent cylindrical-shaped cutting portion that forms an upwardly inclined wall at the edge of the bottom of the hole that has approximately the same angle as the angle of the spindle on which the cutter is rotatably mounted, and which is of suflicient area tocause a right-angle thrust on -the spindle when the drill is in use, thereby reducing the tendency of .the cutter to bind on its bearing, reducing the tendency of the edge portion of the cutter to wear'down quickly, and also permitting the use of'a straight bearing for the cutter which can be manufactured at a lower cost than the tapered bearings now generally used for thetapered cutters of rota-ry' boring drills.

Another object-is to provide a cutter of the character just described which is also equipped with a cutting surface that acts on the side wall of the hole so as to maintain the clearance for the drill head. And still another object is to provide a cutter for rotary boring drills that comprises av cylindrica cutting portion which is appr0Xi mately concentric .with the axis of rotation of the cutter, a substantially frusto-conicalshaped portion arranged atone side of said cylindrical portion and provided with sets of radially-disposed chisel-teeth of different pitch, and an oppositely tapered cutting a portion on the other side of said cylindrical portion for removing the material from the u side of the hole so as to maintain suflicient clearance for the drill head.

Figure .1 of the drawings is a sideeleva- :tional view of a rotary boring drill equipped withcuttersconstructed in accordance with .myinvention; and .Figs. 2 and 3 are elevational ,views of the cutters showing various klnds of-cutting surfaces the cutters can be provided with.

Referringto-Fig. Lof the drawings which illustrates atype of rotary boring drill now in-generaluse, A designates the head ofthe drill, and B designates two cutters rotatably mounted on said head in such a manner that their axes of rotation are inclined downwardly and inwardly towardthe longitudinal axis-0r vertical center of the drill head. Each of said cutters is provided with a cy-. lindrical-shaped cutting portion 1, a tapered cuttingportion2 of approximately frustoconical shape arranged on one side of said cylindrical-portion, .and .an oppositely tapered cutting portion 3 arranged on the other 1 side of said cylindrical portion 1.

Whenthe drill is inoperation the frustoconical-shaped portions 2 of the.cutters act on the bottom of the hole, and the oppositely tapered ,portions 3 of the cutters act on the side wall of the hole. The cylindrical-shapedportihns 1 of the cutters are preferably concentric with the spindles C on which the cutters are mounted, and these cylindrical portions 1 form an upwardlv inclined surface to at the outer edge of the bottom of the hole which-has approximately the-same ang1e' as:the angleof the spindle C, the cylindrical portions 1 of the cutters being of .suflicient area to cause a right-angle thrust on the spindles. vAs shown in Fig. 1 the upwardly inclined surface a: commences, at a point .within the marginal limits of the head and terminates in the side wall of the ;hole at a pointbeyond the marginal limits of the head. One advantage of such a cutter is that a straight bearing cah be used with same, owing tothe factthat the cylindrical-shaped portion '1 of thecutter formsra bearing surface x at the bottom of the hole which is oftsuificient area and arranged at suchan angle that the thrust on permits the use of a straight bearing notprovide which be manufactured at less cost than the tapered bearings now generally used on rotary boring drills that are equipped with substantially frusto-conical-sha ed cutters.

Furthermore, such a cutter wil not wear down quickl owing to the fact that 1t is angular portion at the oint where thetwo portions of the cutter. w 'ch act on the side wall'and on the bottom of the hole meet.

Various means may be employed for retainin the' cutters on their spindles, and while have herein illustrated one type of mounting that is eflicient and inexpens1ve to manufacture, I wish it to be understood that my invention is not limited to such a structure for the cutters could be mounted on the head inany suitable way without departin from the spirit of my invention.

n the structure illustrated in Fig. 1 a bearing or bushing 4 that is screwed onto the spindle-C is provided with a laterally projecting-flange 4" that laps over a ring 5 onto which the cutter B is screwed or permanently connected in any other suitable man- ;ner, said ring 5 cooperating with theflange P on the bushing to prevent the cutter from moving longitudinally of its hearing. The surfaces on the bushing 4 on which the cutter B rotates are cylindrical or parallel with the axis of rotation of the cutter, and therefore the bushing can be manufactured at a far as my broad idea is concerned, but I prefer to provide the approximately frusto-' conical-shaped portion 2 of the cutter with sets of chisel-teeth e ande that radiate from "the apex or small end of the cutter, the teeth of the different sets being of diiferent pitch a; as to cause the material at the bottom of the hole tobe cut finely or divided into small .particles.(In the form illustrated .in Fig.

1 the cu ing surface on the cylindricalshaped part 1 of the cutter and on the oppositely tapered portion 3 is formed by continuations of the chisel-teeth e and e. An-

with a sharp edge or sharp other type of cutting surface is illusti ated in Fig. 2 wherein the reference character f designates spiral teeth or a continuous spiral tooth that winds around the cutter numerous times over-the inde endent portions 1, 2 and 3 of the cutter. the cutter illus trated in Fig. 3 the cutting surface on the frustorcom'cal-shaped portion 2 of the cutter is made up of radially-disposed chisel-teeth g, and the cutting surface on the oppositely taperedv ortion 3 of the cutter is also formed by chise -teeth g. The cutting surface on the cylindrical-shaped portion 1 of the cutter consists of spiral teeth 9* or a continuous spiral tooth that extends aroundtlie cutter a number of times, thus forminga relatively great-cutting area.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is: I

1. A rotary boring drill provided with a rotatable cutter whose axis of rotation is inclined downwardly and inwardly toward the vertical center of the drill head, said cutter having a substantially frusto-conicalshaped portion that acts on the bottom of the hole, and a cylindrical-shaped portion arranged at the base of said frusto-conicalshaped portion for forming an upwardly inclined surface adjacent the outer edge of the bottom of the hole whose lower edge lies in the vertical plane of the drill head, the cutting surface on said ap roximatel frustoconical-shaped portion eing ma e up of sets of radially-disposed chisel-teeth of diffrent pitch.

2. A rotatable cutter for rotary boring drills providedwith a substantially frustoc'onical-shaped cutting portion that acts on the bottom of the hole, an oppositely tapered portion that acts on the side wall of the hole, and a cylindrical-shaped cutting portion arranged intermediate said oppositely ta red portions for forming an upwardly inc ed surface adjacent the outer edge of the bottom of the hole,-the cutting'surface on said frusto-conical-shaped portion being composed of sets of. radially-disposed chiselteeth of diflerent pitch.

In testimony whereof I hereunto aifix my signature in the presence of two'witnesses,

this 16" day of February 1914.

HOWARD HUGHES.

Witnesses:

L. A. GooBoLn, C. E. REED. 

